Underfeed stoker



May 26, 1925. 1,539,208

M. RATEL UNDERFEED STOKER Filed Aug. 16, 1920 3 Sheets-Sheet 1 QR. g I

May 26, 1925. 1,539,208

M.RATEL UNDERFEED S TOKER Filed Aug. 16, 1920 3 Sheets-Sheet 2 UNDERFEED STOKER Filed Aug. 16, 1920 3 Sheets-Sheet 5 m drtegiztoz aftozuu Patented ma 2 192.5.

PATENT-O FFICE.

s mentor: Jam-ran, or new YORK, n. Y. a

l v UNDERFEED STOKER."

Application filed August 16, 1920. Serial No. 403,905.

To all whom it may-concern." I

Be it knownthat I, MAURICE RATEL, a

citizenof the French Republic, and a resident of New York city, have invented new and useful Improvements in Underfeed;

Stokers, which invention is fully set forth in the following specification;

This inventionrelates to automatic underfeed stokers, and has for its objects to so improve the construction of such stokers that approximately complete combustion of the fuel may be obtained, that wear and tear on the elements of the 'stoker may be decreased, and that repairs when requlred may be. made at the minimum .cost in time and money.

One of the fundamental faults ofundei' v feed stokers, as heretofore in use, resides in the fact that such stokersproduce an in eilicient; utilization of the fuel employed,

particularly when such fuel gives .a fusible ash. This results from the fact that there is a tendency to form very large lumps having vitrified surfaces which prevent the passage of air necessary for combustion. In fact,

in some cases'the entire surface of the fuel bed becomesfused intoa single mass, com- 1 pletely stopping the passage of air therethrough and hence rendering efficient com bustion impossible.

Moreover, in underfeed stokers using twyers, it has been found necessary, when'a twyer has been burned out or injured, ,to draw. the fire and remove the entire twyer after waiting a sufiicient length of time for the stoker to cool down-to a temperature where it is possible to work on it. This burning .out of twyers, or destruction thereof by action of the fusible ash of the fuel,

is due to the tendency of the clinkers o1" fusible ash to stick to the surface thereof.

This trouble likewise occurs in the walls of the furnace or Stoker itself, causing a t-ively avoided, and to provide twyersqvhich breakage or wearing awayfof the walls when the clinkers are removed ,by shearing or other forceful action.

The object of the present invention is to provide an underfeed stoker in which the formation of lumps or large surfaces impervious to the passage of air may be effecwill furnish a sufiicie'nt supply of air to effect complete combustion of the fuel, and

which at the same time shall resist the tend ency of the fusible ash or clinkers to stick or a here thereto. Furthermore, it is an object of the invention to provide the stoker with walls which are so formed and maintained at such a'temperature that'the fusible ash or clinkers will not readily adhere thereto. Still. another object is to provide twyers of such construction that, when a portion or part thereof have become burned out or destroyed. such part can be readily removed and-replaced by a new part without disturbing the entire twyer.

Furthermore, it is an object of the invention tokeep the twyers and the walls of the stokei' cooled by the passage therethrough or thereoverof a combustion-supporting or oxidizing fluid which willcool the walls and the twyersb y absorbing heat therefrom, and which fluid itself thereby becomes heated and isv then conducted through the twyer or suitable grate-bars to the fuel or ash bed to support combustion. The combustion-supporting or oxidizing'fluid may be either air,

steam. or water-spray, air being preferably employed as the combustion-supporting or oxidizing fluid which is passed through the twyers', while steam or water-spray is pre-T ferred in the final stages where the'fuel has? reached approximately a condition of ash lllut while still containing some unburned car- Other objects of the invention will app ar in the description following.

The invention is capable of receiving a of illustration only and are not designed to define the limits of the invention, reference being bad to the appended claims for the 1 purpose.

III-Said drawings Fig. ,1 is a longitudinal section through, i

the stoke! on the line 1-. 1 of Fig. 5,1001;- mg 111 the direction of the' a.rrow-;

Fig. 2 is a broken perspective detail of.

the meansfor operating the central pusher in each retort;

. Fig. 3 is a sectional. view on the line '33 ing the latera-l pushers in each retort;-

Fig. 4 is a shown in 1, parts being broken' a'way; Fig. 5 is a cross section on the line' 5.-5 of Fig. 1;

of Fig. 1, illustrating the means for operat- Fig. 6 is a side elevation of one of the plan view of part of the str ker-' sired, a single hopper may "be employed for the entire series of retorts. These retorts 3, 3, 3 alternate with the twyers 4, 4, and fuel is supplied to the retorts from the hoppers 2 by rams 5, which rams. are driven by crank-shaft 6 to which they are so articufated that no two adjacent rams can simultaneously move in the same direction throughout their respective strokes. These rams advance the fuel from the. hoppers to the upper ends of the retorts 3, after which the advance of the fuel between the twyers is effected by a lurality of compound pushers having their longitudinal axes in difi'erentvertical planes. Said compound pushers are laterally disposed with respect to each other and preferably arranged side by side in each retort. As here shown each compound pusher comprises a bar 11 and a plurality of pusher elements 7 secured on said, bar and constituting a unit and each retort contains a set of compound pushers comprising a central compound pusher 7 and two lateral compound pushers 7". Means are provided for driving the lateral compound pushers of each set in one direction while the central compound pushers are simultaneously driven in the reverse direction, and such propelling means are also provided with adjustable features whereby the strokes of the lateral and the central compound pushers may be varied or adjusted. Referring to Figs. 1 and 2, 8 is a lug depending from the ram 5 between two pins -9, 9 inserted in openings 10, 10 in the pusher bar 11 of the central compound pusher 7 (see Fig. 2). It will be apparent that, by adjusting the pins 9, 9 in the holes 10. on the bar 11, the throw of the central bar can be adjusted so as to nearly coincide with that of the ram 5, or may be materially less than that of the ram, as may be desired.

Still referrin to Fig. 1, 12 is a lug depending from t e connecting rod 13 of the ram 5, to which is articulated a link bar 14 whose lower end is provided with a slot a in which the pin 15, fixed to the lower end of an arm 16 of the toothed sector 17 may slide to thrust block b which may be adjusted by means of a screw 0 and a nut d (as shown on the fig.) or by any other suitable means permitting adjustment to vary the stroke of the arm 16. The toothes sector r s me 17 engages a rack 18 on the under side of the pusher bar 19 of one of the lateral compound pushers (see Figs. 1 and 3). It will be observed that the forward movement of the ram 5 produces a forward movement of the central pusher bar 11, while such forward movement of the ram produces a reverse or rearward movement of the pusher bars 19 so that the central bar advances while the lateral bars are withdrawn and that the extent of thrust of the central and lateral bars may be adjusted as desired. Furthermore, inasmuch as no two adjacent rams are moving in the same direction at the same time throughout their respective strokes, it will be clear that in no two adjacent retorts are the lateral pushers moving -ly and just about completing its rearward In the next retort, the pushers are stroke. shown in the position which they occupy on the. forward stroke of the ram 5 about midway of the stroke. In the nextv retort, the pushers are shown in the position which they assumewhen the ram 5 connected therewith has just about completed its forward stroke, and the other retort, where the figure is broken away, shows the pushers in the position which they occupy when the ram 5 connected therewith is moving forward and is about midway of its stroke. A consideration of the several series of pushers and their respective directions of movement will make it clear that they will serve to impart a constantly undulating or wave-like action to the fuel bed, whereby it is kept constantly broken up .and the fusingof the fuel into compact masses imperviousto air is effectively prevented. v

It will also be observed from an inspection of Fig. 1 that there is a fuel bed of substantially. uniform thickness maintained throughout the combustion area and that, by reason of the very slight incline of twyers 4, avalanching or precipitous sliding forward of the fuel is prevented, the feed of the fuel being substantially dependent upon the advancing action of the several com-' pound pushers.

interposed between the several retorts are the twyers 4. These twyers are made of any suitable material and are provided with corrugated surfaces, as will be'readily understood from an inspection of Fig. 7 Thesecorrugations form little depressions orvalleys for receiving the ashes and preventlng the fuel in active combustionfrom coming of the slot being -materially "less than the diameter of the opening 22. These twyers 4 have plain adjacent ends, that is, they have no interlocking engagement with each other, dependence being placed upon the locking means hereinafter described to hold them in proper position. The several twyers 4 are locked in position by a round locking bar 20 (Figs. 6 and 7) provided with flattened parts 24 which have a smaller thickness than the width of the slots 23. By turning the twyer lockingbar 20, through an angle of 90, it will be seen that any twyer 4 requiring replacement may be readily lifted out and another one placed in position, and

the bar 20 turned to the position shown in Fig. 7 when the repair is completed.

The several twyers are open at their under side, as will be understood from an inspection of Figs. 1, 5 and 7, and the combustion-supporting or oxidizing. fluid, enters the twyer. through the bottom opening and obtains exit into the fuel bed through openings 25, 26, the lower openings 25 being of materially greater area than the openings 26, to the end that a greater amount of combustion-supporting or oxidizing fluid may pass through the lower openings than through the upper openings. 1

As the fuel is advanced from the upper to the lower side of the fuel bed and com bustion of the fuel progresses, the ash or refuse, while still containing possible particles of unburned fuel, isadvanced by the pushers into a trough-shaped hopper 27, Fig. 1, at the lower side thereof. which trough or hopper has its lateral walls composed of corrugated grates 27'. These lateral walls approach each other near the bottom which is open and through which the refuse is deposited onto a dump plate 28, Fig. 1,

hinged at 29 and provided with any suitable means, here shown as a system of pivoted links 30, whereby the size of the discharge opening 31, through which the refuse is ejected into the dump 32. may be adjusted.

The side walls 33 of the stoke'r are cor rugated, as shown in elevation in Fig. 1 and in plan in Fig. 4, thereby affording greater surface for the cooling action of the combustion-supporting or oxidizing fluid which is caused to pass on the rear side thereof, as hereinafter explained, and presenting smaller surfaces to which the fusible ash or clinker of the fuel may adhere and fromwhich it may be more readily removed than if the same were a flat surface.

The main supply of combustion-supporting or oxidizing fluid isreceived through a tunnel 34 (Fig. 1), from which it enters directly into a closed chamber 35, under the retorts, through a throator passage 36 suitably controlled by a valve 37. Such to vary said supply in the sucessive parts of the grates corresponding to successive dampers 38, horizontal partitions being shown to form a succession of air chambers in these grates. Leading from the tunnel 34 is a valved conduit 39 (Fig. 1), communicating with a conduit 39, which conveys the combustion-supporting fluid into the side chambers 41 where it'serves to not only cool the corrugated walls of thestoker but to itself become heated. From the chamber 41, the

combustionesupporting fluid is conducted to the chamber 35 through openings 42, one of which is shown in Fig. 5, a corresponding opening of course being located on the other side of the Stoker.

7 Referring now to Figs. 1 and 4, the combustion-supporting or oxidizing fluid not only passes along the chamber 41 but is also passed along the chamber 41 in the walls of which are openings 43 through which the combustion-supporting or oxidizing fluid passes to the rear of the grates 27. not only serves to keep the grates 27 cooled to the point where injury thereto may be avoided, but also supplies combustion-supporting or oxidizing fluid which passes This combustion-supporting,fluid absorbs heat through the grates to complete the combustion in the refuse contained in the hopper 27.

After complete combustion has been secured, the refuse falls upon the dump'plate 28 from which it is rearwardly ejected through opening 31 by rams 44 (Fig. 1) which receive reciprocating motion through series of links 45, 45", 45, and 45 and levers 45 and 45 connecting them with the rods 13 of the rams 5. Preferably. there is a duplicate set of these links and levers, one for either side of the ram 44 as shown in the broken-away portion of Fig. 4, so that the pushers move uniformly and evenly backward and forward. Thrust members set at the upper ends 46 of the links 45 permit adjustment to vary the stroke of the rams 44, the ends 46 having suitably spaced openings, providing with the thrust members, adjustable connections with the rods 13.

It will be seen, by the means described,

' ing, breaking motion imparted to the fuel bed, whereby the formation of large agglomerated masses or surfaces is entirely avoided; that the adherence of fusible ash or clinkers to the walls, grates, and the tw'yers of the stoker is avoided through the provision of the corrugated surfaces, in combination with the cooling action of the combustion-supporting or oxidizing fluid; that ample provision is made for completing the combustion of any carbon that may be advanced with the 'ash or refuse into-the hop-per 27; and that means are provided whereby the combustion-supporting or oxidizing fluid not only performs its combus tion-supporting or oxidizing function but it more efliciently performs that by reason of the fact that it is itself heated while at the walls of the stoker also the walls of the the same time coolin and the twyers an hopper 27. The combustion supporting or such repairs are required, and particularly expeditiously effected than in prior con to the twyers, they may be more cheaply and structions. l a

It will also be apparent to those skilled in the art that the invention iscapable of I being embodied in other forms than those herein specifically shown without departing from the spirit of'the invent-ion. Such forms are included in the appended claims.

While the invention as illustrated and above described is embodied inan underfeed stoker, it is to be expressly understood that certain features thereof may be used in other types of stokers. Reference is there fore to be had to the claims hereto appended for a definition of the limits of the invention.

What is claimedcis:'

1. In an automatic stoker, a fuel retort or trough, a set of compound pushers in said retort having their longitudinal axes in different vertical planes, and means for moving adjacent compound pushers in opposite directions. I

2. In an automatic stoker, a fuel retort or trough, a set of compound pushers in the retort laterally disposed with respect to each other and means for moving adjacent compound pushers in opposite directions.

assaace 3. In an automatic stoker, a fuel retort or trough, a set of compound pushers insaid retort laterally disposed with respect to each other, means for moving adjacent compound pushers in opposite directions, and means for adjusting the strokes of said compound pushers.

4. In an automatic stoker, a fuel retort or trough, twyers at the sides of said retort or trough, an ash receiving hop-per at the rear of the retort and provided with an opening in the bottom thereof, a refuse receiving dump plate arranged below said hopper in spacedrelation therewith to provide adischarge opening at the rear of the furnace, a reciprocating pusher for advancing refuse over said plateand through said opening, and means for adjusting the stroke of said pusher. i

5. In an automatic stoker, the combination of aseries of retorts, twyers alternating with said retorts, a combustion-supporting fluid supply for said twyers, means supplying fuel to the outer end of each retort, a centrally located fuel-advancing pusher in each retort, a pair of fuel-advancing pushers one on eachside of said central pusher, and means reciprocating the central pusher and said pair of pushers simultaneously but in opposite directions.

6. In anautomatic stoker, the combination of a series of retorts, twyers alternating with said retorts, a combustion-supporting fluid supply for said twyers, means sup: plying fuel to-the outer end of each retort,

a centrally located fuel-advancing pusher in each retort, a pair of fuel-advancing pushers one on each side of said central pusher, means reciprocating said central pusher and said pair of pushers simultaneously but in opposite directions, and means for adjusting the throw of said pair of pushers.

7. In an automatic stoker, the combination of a series of alternating twyers and retorts means supplying fuel to the outer ends of said retorts-with means advancing the fuel along the same, means supplying a combustion supporting fluid to said twyers, an ash receiving hopper at the inner ends of said retorts and having its front and rear walls formed of grates, means supplying a com-' bustion supporting fluid to said hopperthrough said grates, and means for varying the supply of combustion supporting fluid delivered through successive portions of said grates I 8. In an automatic stoker, the combination'of a series of alternating twyers and retorts, means supplying fuel to the outer ends of said retorts with means advancing the fuel along the same, means supplying a combustion supporting fluid to-said twyers, a separately formed ash receiving hopper at the inner ends of said retorts, and having its front and rear walls formedflof corrugated grates. means supplying a combustion supporting fluid to said hopper through said grates. and means for varying the supply 'of combustion supporting. fluid delivered ing with said retorts, each of said twyers.

being composed of a series of non-interlockmg uxtaposed sectlons having depending apertured lugs withjslots leading from the apertures thereof, and means rotatably mounted in the apertures of said lugs for holding said sections in position; said means coacting with said slots by rotation of the former. to. provide for independent removal of one or more of said sections.

10. In an automatic stoker, thewcombination of a series of retorts, twyers alternating with said retorts. each of said twyers being composed of a series of non-interlocking juxtaposed sections having depending apertured lugs with slots leading from the apertures thereof, and a rod rotatably mounted in the apertures of said lugs for binding the sections together, the portions of said rod in engagement with said lugs being of greater width than said slots and adapted on rotation of the rod to register with the slots whereby one or more of said sections may be removed for repairs or replacement.

11. In an automatic'stoker, the combinatlon of a' series of retorts, twyers alternating with said retorts, each of said twyers being composed of a series of noninterlockingjuxtaposed sections having depending lugs provided withopenings and slots ex: tending therefrom. and a rod. of greater width than thickness extending through said openings and capable of passing through the slots'when turned so that its lesser di- .mension coincides with the slots, whereby in dividual sections of the twyers' may be removed forrepairs or replacement. 12. in an automatic Stoker, a series of re- 7 torts, twyers alternating with said retorts,

means supplying a combustion supporting fluid to said twyers, a'fu'el feeding ram at the outer end ofeach retort, a pluralitvof compound pushers disposed side byside in each retort, and means operatively connecting-sald ram with sa1d compound pushers for reciprocating the adjacent compound pushers as units, in opposite directions.

13. In an automatic stoker, a series of re-' torts, twyers alternating with said retorts,

means supplying a combustion supporting fluid to said'twyers, a fuel-feeding ram at the outer end of e'achretort, a plurality of compound fuel pushersdisposed side by side in each retort, and adjustable means operatively connecting said ram with said compoimd pushers for moving the'adj acent comdirections.

14. In an automatic stoker, a series of re- -torts,,t'wy'ers alteirnating with said retorts,

means supplying a combustion supportingfluid to said twyers, a fuel-feeding ram at the outer end of each retort,- for supplying fuel thereto, means advancing the fuel along each retort comprising a plurality of compound pushers side by side therein, means operatively connecting said ram with said compound pushers for moving the adjacent compound pushers in opposite directions,

and means for varying the extent of move- 7 ment of said compound pushers.

15. In an automatic Stoker, a series of ret'orts, twyers alternating with said retorts, means supplying a combustion supporting fluid to said twyers, means supplying fuel to the outer end of each retort including a fuel-feeding ram,means advancing the fuel along each retort comprising a plurality of compound pushersdispo'sed side-by side in each retort, means reciprocating adjacent compound pushers in opposite directions, said means including adjustable connections between said ram and said compound pushers for varying the extent of movement of the adjacent compound pushers vas units in opposite directions. 16. In an underfeed stoker, the combination with a series of retorts. corrugated sectional twyers alternating therewitln the walls of said twyers having a series of slotted openings, one above the other and decreasing in area from the lowest to the highest opening.

p 17 In a gravity untlerfeed stolrer, the combination of a series of alternating twyers and retorts, providing a fuel'bed, means Mil sup-plying a combustion supporting fluid to the fuel bed, an upwardly flaring separately formed corrugated hopper at the discharge ends of said retorts having'openings in its front and rear walls, means surrounding and supplying a combustion supporting fluid to the contents of said hopper through said openings, and means-for varying thein the bottom thereof,- a refuse-receiving dump plate arranged below said hopper in spaced relationctherewith, and means for pushing the refuse over saidplate and eject- I ing the same rearwardly ofjsa'id' hopper.

19. In-an automatic stoken'the combination of a series of retorts and twyers alternating therewith, meanssupplying fuel to 'the outer ends of said retorts, means ad vancing the fuel through said retorts, an

ash-receiving hopper at the inner ends of said retorts and provided with an opening in the bottom thereof, a refuse-receiving dump plate arranged below said hopper in spaced relation therewith to provide a refuse discharge opening at the rear of the hopper, means for. regulating the size of said opening, and means for advancing the refuse over said plate and ejecting thesame' through said refuse discharge opening. 7

20. In an automatic stoker, the combinae tion of a seriesof retorts and twyers alternating therewith, means supplying fuel to the front ends of said retorts, means advancingx the fuel through said retorts, an ash-receiving hopper at the rear ends of said retorts and having an. opening in the bottom thereof, a refuse-receiving dump plate arranged below said hopper in spaced relation therewith to provide a refuse discharge opening at the rear of the hopper, and means for pushing the refuse over said plate and ejecting the same through said refuse discharge opening.

21. In an automatic stoker, the combination of a series of retorts and twyers alternating therewith, means supplying fuel to the outer ends of said retorts, means advancing the fuel through said retorts, an ash-receiving hopper at the-inner ends of said retorts and providedwith an opening in the bottom thereof, a refuse-receiving dump plate arranged below said hopper spaced relation therewith to provide a refuse discharge opening at the rear of the hopper, and a reciprocating pusher for advancing the refuse over said plate and through said refuse discharge opening.

22. In an automatic stoker, a series of alternating twyers andretorts, fuel feeding fluid through said chamber, whereby said walls are cooled and said fluid is heated, and means conducting said heated fluid to the fuel bed to support combustion.

23. In an automatic stoker,-a twyer composed of a series of juxtaposed non-interlocking sections having apertured lugs with slots lea-ding from the apertures thereof, and a rod of greater width than thickness insertable through said slotsand rotatable in said apertures, said rod'securing the sec tions together on rotation ofthe same to one position and registering with said slots to provide for independent. removal of one or -more sections on rotation of the rodto an:

other position. 1

,In testimony whereof I have signed this specification. V

MAURICE layman 

